Controlling device for electric motors



(No Model.) 2 Sheets-Sheet 1.

P. B. HERDMAN.

CONTROLLING DEVICE FOR ELEOTRIG MOTORS. No. 519,121. Patented May 1,1894.

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(No Model.) 2 Sheets-Sheet 2. F. E. HERDMAN.

CONTROLLING DEVIGE FOR ELECTRIC MOTORS.-

No. 519,121. Patented May 1,1894.

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UNITED STATES PATENT OFFICE.

FRANK E. HERDMAN, OF INDIANAPOLIS, INDIANA.

CONTROLLING DEVICE FOR ELECTRIC MOTORS.

SPECIFICATION forming part of Letters Patent No. 519,121, dated May 1,1894.

Application filed July 19, 1892. Renewed January 11, 1894. Serial No.49654:7- (No model.)

.To all whom it may concern:

Be it known that I, FRANK E. HERDMAN, a ci tlzen of the United States,residing at Indianapolis, county, of Marion, and State of Indiana, haveinvented a new and useful Improvement in Electric Motors, of which thefollowing is a full, clear, and exact descrip tion, reference being hadto the accompanying drawings, which form a part of this specification.

The objects of this invention are to give better contact and greaterefficiency in the consumption of the current for the operation ofelectric motors in use with elevators or in any manner of use where theyare subject to being continually stopped, started and reversed. One ofthe difficulties to be overcome, especially with elevators, is the greatstrain upon the main circuit and the central station when starting.Thus, the moment before the armature of the motor commences to revolveafter the current is turned on the same, an excessive amount of currentis liable to pass through it, causing a momentary strain upon the powersupplying the current. As soon as the armature commences to revolve,this strain is gradually reduced, until the motor obtains its speed.

My invention consists in certain improved wiring and electricconnection, so that excessive strength is given to the fields at thetime the current is thrown on to the motor, and the armature thusrevolves that much quicker, and also obtains its speed in much lesstime, than if the fields were not strengthened, thereby reducing thestrain on the power station. Of course, this greater strength of thefields, if maintained, would prevent the motor from running at its fullspeed. Consequently, the strength of the fields is reduced as the motorincreases its speed to the maximumat the same time afiording the meansof reducing to the minimum the strain upon the power station instarting.

In the drawings-Figure 1 is a diagrammatical view. Fig. 2 is adiagrammatical view. Fig. 3 is a diagrammatical view. Fig. 4 is a faceview of lever of Fig. 3. Fig. 5 is a plan view of lever of Fig. 3. Figs.6, 7 and 8 are detail views of the switch roller.

M is the motor.

Ais the rheostat box. In this box is the wooden drum A, loose on theshaft a, having bearings a, (1. This drum has upon its face two plates,B and C. These plates are of peculiar shape and Wound around the drum ina peculiar manner. Thus the plate B has a solid portion 1) at one end,while at the other end it is formed into two portions, 1), b separatedby a space. The plate 0, in a similar mannor, has at one end the solidportion 0, and at the other end the two portions 0', c separated by aspace. These plates are wound around the drum in a peculiar manner, sothat they cross one another. At their point of passing, the two platesare separated by an insulated strip.

Beneath the drum A, and in contact with the same, are the two brushes 3and 4, one in contact with plate B, and the other in contact with plate0.. The brush 3 is connected directly with the main circuit, the brush 4being in direct electrical connection with the other pole of currentsupply, the field of the motor being also in direct electricalconnection with the source of current supply. In contact with the top ofthe cylinder A are the brushes 5, 5 and 6, 6. The brushes 6, 6', are inelectrical connection with the solenoid D. Brush 5 is in electricalconnection with the contact 30; the other brush 5' is. in electricalconnection with the armature of the motor.

E is an arm connected at one end to the.

solenoid core and at the other end to a dash pot F.

G is an arm connected to the arm E, and carrying a brush g.

H are the resistances, and the arm G from the point g is in electricalconnection with the armature of the motor and has brush 9',

so that through the resistances and arm G,

brush 5 is in electrical connection with the armature of the motor. Thefields of the motor being excited in the usual way, with the wiring forthe best results for its maximum speed and connected to the maincircuit, as hereinbefore described; there are placed, in addition tothis arrangement, on the outside of the regular coils, or on a separatespool in the field magnet, a succession of coils, K, K, K K, 850. Eachindividual coil of these coils is brought to the surface and connectedon one side with one pole of the main circuit,

and on the other side with its individual contacts, It, S, T. Thecontact Q is connected with the remaining pole of the main circuit.These contacts are so arranged that contact Q extends beyond the limitof contacts It, S,- and T, while contacts R, S and T are of differentlengths, both contact Q and contacts R, S and T are in line of movementof arm G, and these contacts R, S and T are so arranged that as the armG passes over the rheostat face, it cuts out one of these contacts at atime. To the arm G is attached a brush J, which passes over the contactsand is insulated from the arm G. Thus when the switch is operated toadmit the current and the solenoid electrified, the arm G travels overthe rheostat. As the arm G moves, first contact R is cut out, as itpasses beyond said contact, then contact S, and finally contact T. Thus,as the arm G travels over the rheostat face, one coil at a time of theentire coils K, K, K &c., is cut out of the field circuit, therebyreducing it. In this way, at the starting, the fields are given greaterstrength, thus giving the armature greater power of starting, with lessstrain on the central station.

Instead of connecting the armature directly with the lever G, I canconnect it through a solenoid 25 (see Fig. 2), the core of which isprovided with a trip 26, which works in a series of teeth on a wheel 27,attached to the arm G and turning 011 the same pivot as said arm. Nhenthe current reaches the proper limit, to prevent strain on the motor,this solenoid 26 will draw in the core and raise the trip 26 until it isin contact with the teeth of wheel 27, thereby preventing any furthermovement of the arm G, thus in consequence retaining a certain number ofcoils K, K K in circuit, and also retainingacertain amount of resistancein the armature circuit. when the speed of the motor increases so as toreduce the amount of current passing through this solenoid to thearmature to within the maximum amount, then the core drops, releasingthe trip from the teeth and allowing the arm g to continue its movementto the right, and cutting the resistances out of the armature circuit,also cutting the additional strength out of the fields. If the currentpassing through becomes excessive, the solenoid would at once act andagain check the movement, thereby preventing an excessive amount ofcurrent passing. The brush J, instead of being carried by the arm G, maybe carried by an independent ar (see Figs. 3, t and 5). This arm 32 ispivoted to the arm E at the same place that the arm G is pivoted (seeFig. 5) and has the toothed wheel 27, in the teeth of which the trip 26works. A weight 33 is attached to arm 32 and said arm has a projection34; so that said arm 32 and arm G may work independently, the weight 33moving said arm, and the trip 26 and solenoid 25 regulating the movementof said arm. When the current is turned off, the

arm G, on its return movement, strikes the projection Set, carrying thearm back with 1t.

Having now fully described my invention, what I claim, and desire toprotect by Letters Patent, is

1. In combination, a source oE current supply, a switch, electricalconnection between said switch and the source of current supply, arheostat, electrical connection between said rheostat and switch, asolenoid, electrical connection between said solenoid and switch, an armoperated by the core of said solenoid and adapted to travel over saidrheostat, a motor,

electrical connection between the source of current supply and fieldcoils, electrical connection between the armature of motor and switch,and electrical connection between said armature and arm operated bysolenoid, coils around the field magnets, contacts to which said coilsare separately connected, said contacts being of different length, saidcoils also connected with the main circuit, and a contact connected withthe other pole of the main circuit, and an arm adapted to pass over saidcontacts.

2. In combination a source of current supply, a switch, electricalconnection between said switch and the source of current supply,resistances, electrical connection between said resistances and switch,a solenoid, electrical connection between said solenoid and switch, anarm operated by the core of said solenoid and adapted to travel oversaid resistances, a solenoid in electrical connection with said arm, amotor, electrical connection between the source of current supply andfield coils electrical connection between the armature of the motor andthe switch, electrical connection between said armature and solenoid inelectrical connection with the arm, coils around the field magnets,contacts to which said coils are separately connected, said contactsbeing of different length, said coils also connected with the maincircuit, a contact connected with the other pole of the main circuit, anarm adapted to pass over said contacts, a toothed wheel on said arm, atrip attached to the core of the solenoid in electrical connection withthe armature, said trip being adapted to work in the teeth of saidtoothed wheel.

3. In combination, a source of current sup ply, resistances electricalconnection between said resistances and the source of current supply, anarm adapted to travel over said resistances, a motor, electricalconnection between the source of current supply and the field coils,electrical connection between the armature of the motor and the sourceof current supply, electrical connection between said armature and saidarm, coils around the field magnets, contacts to which said coils areseparately connected, said contacts bein g of different length, saidcoils also connected with the main circuit and a contact connected withthe other pole of the main cir- ICO cuit and an arm adapted to pass oversaid contacts.

4:. In combination, a source of current supply, resistances electricalconnectionbetween 5 said resistance and the source of current supply, anarm adapted to travel over said resistance, a solenoid in electricalconnection with said arm, a motor electrical connection between thesource of current supply and the 10 field coils, electrical connectionbetween the armature of the motor and the switch electrical connectionbetween said armature and solenoid in electrical connection with thearm, coils around the field magnets, contacts 15 to which said coils areseparately connected,

Witnesses:

W. L. ROBINSON, W. V. MARTIN.

